[airq] fix table in readme that broke rendering markup (openhab#13937)

Signed-off-by: Hilbrand Bouwkamp <hilbrand@h72.nl>

bundles/org.openhab.binding.airq/README.md

@@ -44,7 +44,7 @@ For the Maximum Error channels just add `_maxerr` to the channel names.
 The rw column is empty if the channel is only readable, w if the channel can be written and rw if it allows both to be read and written.
 
 | channel | type | rw | description |
-|---------------------------|----------------------|--------------------------------------------------------------------------|
+|---------------------------|----------------------|----|---------------------------------------------------------------------|
 | status | String | | Status of the sensors (usually "OK") |
 | avgFineDustSize | Number:Length | | Average size of Fine Dust [experimental] |
 | fineDustCnt00_3 | Number:Dimensionless | | Fine Dust >0,3 µm |